The control of phytopathogenic fungi is of great economic importance since fungal growth on plants or on parts of plants inhibits production of foliage, fruit or seed, and diminishes the overall quality of a cultivated crop.
Because of the vast economic ramifications of fungal propagation in agricultural and horticultural cultivations, a broad spectrum of fungicidal and fungistatic products have been developed for general and specific applications.
Of particular interest with respect to the present invention embodiments are fungicide compositions which contain an inorganic bicarbonate or carbonate compound. It is known that bicarbonate and carbonate compounds exhibit fungicidal properties for agricultural purposes.
Phytopathology, 48, 169 (1931) by R. H. Marloth describes studies involving the physiology of fungi. The reference reports studies which demonstrate that sodium and potassium bicarbonate and carbonate salts are toxic to fungi such as Penicillum italicum and Penicillum digitalum.
U.S. Pat. No. 1,560,558 discloses the use of salts such as lithium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium carbonate and ammonium bicarbonate as fungicide ingredients.
U.S. Pat. No. 4,599,233 describes a fungicide composition which consists of sodium bicarbonate in combination with a surface active food emulsifier such as sorbitan monostearate.
Japanese patent 53096319 describes the application of potassium bicarbonate as an active biocide for the control of fungal diseases common to tomato and cucumber plants.
Japanese patent 56043207 describes a biocidal composition containing sodium bicarbonate and a polyglycerol fatty acid ester. The biocide controls Penicillum digitatum on oranges, Sphaerotheca fuligenea on cucumbers, Piricularia oryzae on rice, and mosaic virus on tomatoes.
Japanese patent 60097909 describes a soil fungicide prepared by admixing slaked lime with sodium bicarbonate, potassium bicarbonate, boric acid and phenolphthalein.
Japanese patent 57062208 describes horticultural fungicides in which the addition of sodium bicarbonate to polyoxin or thiophanatemethyl increases the fungicidal activity of the organic biocide against botrytis cinerea on cucumbers.
Japanese patent 58023609 describes an agricultural fungicide composed of a mixture of sodium bicarbonate or potassium bicarbonate with cupric hydroxide, basic copper carbonate or basic copper sulfate. The combination of ingredients exhibits a synergistic fungicidal effect against cucumber early blight, tomato wilt, rice sheath blight, rice blast and citrus canker.
While the fungicidal activities of alkali metal bicarbonates are well-established, there is less certainty concerning the fungicidal activity of the related ammonium bicarbonate. In vitro studies indicate that ammonium bicarbonate often is more effective than sodium or potassium bicarbonate for control of fungus growth. In contradistinction, in vivo application of ammonium bicarbonate generally is not effective for control of foliar fungi. Sodium and potassium bicarbonate but not ammonium bicarbonate are effective for controlling powdery mildew on roses. However, ammonium bicarbonate is efficacious for control of soil fungi such as Sclerotinia sclerotiorum infection of peanut crops.
It appears that ammonium bicarbonate is less effective in plant foliar applications for fungus control because ammonium bicarbonate is less stable than alkali metal bicarbonate under ambient temperature and moisture conditions. The ammonium bicarbonate does not remain intact as an active biocidal entity for a sustained duration and in a sufficient contact concentration to achieve fungus control.
There is a continuing interest in the development of new and more effective fungicides which possess preventive, curative and systemic activity for the protection of cultivated plants, with a minimum of phytotoxic side effects.
Accordingly, it is an object of this invention to provide a dry blend biocide composition which releases at least two bicarbonate ingredients exhibiting fungicidal properties when applied to agricultural and horticultural plants as a powder, an aqueous dispersion, or a solution.
It is another object of this invention to provide a fungicide composition which is an aqueous formulation of ingredients adapted for sustained in situ generation of ammonium bicarbonate when applied to plant foliage.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.